1. Field
The present invention relates generally to current calibration. More specifically, the present invention relates to systems, devices, methods, and computer-readable media for calibrating battery charging current.
2. Background
Modern mobile communication devices, such as cell phones, PDAs, etc., typically use a rechargeable battery. During constant-current (CC) charging of a rechargeable battery (e.g., a Lithium battery), precise control of charging current is essential for both battery safety and user experience. If a charging current for a battery exceeds a threshold level, lifecycle of the battery may be reduced and the battery may be damaged. If the charging current is too low, battery charging time may be increased.
Conventionally, battery charging methods rely on analog battery charging current control. In conventional methods and devices, battery charging current is sensed via a current sensing element, such as a resistor or a field-effect transistor (FET). A current sensing signal may then be fed to an analog control loop to regulate battery current (IBAT) during CC charging. As will be appreciated by a person having ordinary skill in the art, battery current control accuracy is affected by imperfections in analog circuits, such as the amplifier offset, etc. These analog imperfections are process, voltage and temperature (PVT) dependent. Although process variation may be limited, accuracy may be reduced across battery voltage, battery current and charger temperature. Further, achieving reasonable battery current accuracy is extremely challenging with low battery current, since the sensed signal becomes comparable to noise and/or an offset of the circuit. This often results in expensive analog circuit implementation.
A need exists for systems, devices, methods, and computer-readable media for calibrating a charging current. More specifically, a need exists for systems, devices, methods, and computer-readable media for calibrating a charging current with a coulomb counting analog-to-digital converter.